Electric switch



Dec. 4, 1928.

J. D.- HIL/LI'ARD ELECTRIC SWITCH Filed Aug. 26, 1925 Jqhn D. Hilliard,

bld

His Attorney.

Patented Dec. 4, 1928 UNITED STATES 1,694,261 PATENT OFFlCE.

JOHN D. HILLIARD, 0F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC SWITCH.

Application filed August 26, 1925. Serial No. 52,669.

My invention relates to electric switches and, particularly to switches of the fluid break type which, upon the separation of the contacts under abnormally heavy loads, are apt to throw hot insulating fluid or to be ruptured by the great pressure produced therein.

In the development of systems of electrical distribution of power there is a marked tendenc y toward generation in large units. Under short circuit conditions generators of large, capacity are capable of developing i11- stantaneously many times their normal full load current and of sustaining under such conditions currents which are several times greater than normal load. The energy supplied by these large generators is usually distributed through a network of feeders for local consumption in comparatively small load units. Switches installed in such feeder circuits are usually small in capacity to afford sensitive protection and to be economical in first cost, unusual conditions such as loW resistance short circuits being generally provided for by furnishing means to relieve the smaller switches from the duty of clearing the line. There are, however, many installations wherein such protective means are not employed and it is possible that failure may occur in systems having such protective features. Under such conditions the smaller switches are likely to fail when called upon to interrupt currents greatly in excess of their rated capacity. This failure in the case of oil switches is generally caused by the generation of an excessive quantity of gas when a heavy arc is drawn in the liquid and is manifested by the throwing of a considerable amount of highly inflammable oil and the possible deformation of the switch tank.

One objectof my invention is therefore to provide for the sudden relief of excessive pressure which may be generated in the switch.

Other objects are to provide means for preventing injury to persons or property from contact with highly heated and inflammable oil ejected from electric switches, and further to provide a safe and convenient receptacle into which the highly inflammable oil of a switch tank may be readily drawn.

Other objects and advantages of my invention will appear from the appended description of one embodiment thereof, reference being made to the accompanying drawing which forms a part thereof and which is an elevation of a single pole switch of this character, some of the part-s being broken away and others shown in section.

Referring to the drawing, I have shown at 1 the tank of a fluid break switch having the insulating lining 2 and containing the in sulating liquid 3, which for example may be oil, in which the switch contacts separate. The tank bottom i and the lining 5 covering the same are each provided with a central opening and secured to the bottom 1 opposite the opening therein is the ring 6. Plug 7 threaded into this ring carries the breakable member or diaphragm 8 which when the pressure within the tank exceeds a predetermined value is adapted to be ruptured, thus suddenly relieving the pressure. Various materials may be employed in the construction of the member 8 and various means may be employed to seal the tank at this point against leakage such as solder, welding cement etc., depending upon the character of the material used. The pipe 9 is shown threaded to the ring 6 for the purpose of directing the material discharged from the tank upon rupture of the member 8. Located at a safe and convenient place below the tank is an oil sump comprising a reservoir 10 having a perforated cover 11 and a central receiving tube 12 which overlaps the pipe 9. The screens 13 separated by a layer 14 of gravel or quartz pebbles extend across the tube 12 being shown sup ported by cross bars 14. A similar screen 16 covers a layer-17 of gravel. or pebbles on the perforated cover 11.

Under normal conditions of operation the amount of gas and hence the pressure at the operating of the switch will not be sufficient to cause the rupture of the member 8. If, however, under abnormal conditions the pressure rises to such a value that the switch tank is in danger, the member 8 will give way and suddenly relieve the pressure. The hot gases and oil are then shot down through the screens and gravel into the reservoir where the oil is confined but from which the gas may escape, being separated from the oil and cooled below its ignition temperature before reaching the outside air.

lVhat I claim as new and desire to secure by Letters Patent of the United States is:

1. In a fluid break switch, a tank containing an insulating liquid, a diaphragm mount-- ed in the bottom of the tank constructed to be ruptured by an excessive pressure in the tank,

and a receptacle for receiving the gas and liquid ejected through the ruptured diaphragm, said receptacle having corer comprising means for cooling and preventing c nihnstion of the material received therehy.

2. In an electric switch having contacts arranged to separate in an insulatingliquid, an enclosing tank therefor having a pressure relief opening. a closure for said opening; con structcd to ehect a complete uncovering thereof upon the occu 'ence oi a predeterniined pressure in the receptacle having a connection with, openin I torreceiving the gas and liquid discharge 1, neretroni, said receptacle having a cover comprising coolii and separating nialerial whereby the separated liquid is retained in the bottom of the receptacle and the cooled ga. escapes from the top thereof.

3. In an electric switch hzwing contacts arranged to separate in an insulating liquid, an enclosing tank therefor having a pressure rcliet opening, a closure for said opening constructed to etlect a complete uncovering thereof upon the occurrence of a predetermined pressure in the tank, a receptacle having: a pipe connection with said opening for receiving the gas and liquid discharged therefrom, said receptacle having inlet and outlet openings in the upper portion thereof, and cooling and separating n'iaterial covering both of said openings whereby the gas and liquid diaclnireed from the tank are cooled upon entering); the receptacle and the gas further coolei'l upon being discharged therefrom.

In Witness whereof, I have hereunto set 111) hand this 12 h day of August, 1925.

JOHN D. HILLIARD. 

